During the operation of a turbine engine, it may occur that it is necessary to perform an emergency shutdown of the fuel supply. More specifically, in a two-spool bypass turbine engine, if ever the connection between the fan and the low pressure shaft that drives this fan is broken, the fan is no longer able to exert a resistive torque against this low pressure shaft. In this case, if the supply of fuel is not cut off quickly, the high pressure and low pressure bodies risk overspeeding, with the risk of having the blading discs of the turbine stages thereof break under the excessive centrifugal forces produced by the excessively high rotation speeds. The bursting of such a disc can cause much damage to the turbine engine and also even to the other parts of the aircraft. A system is therefore provided to quickly cut off the fuel supply and thus prevent turbine engine overspeeding.
Similarly, a thrust control defect of the turbine engine can result in a high thrust (UHT or “Uncontrolled High Thrust”) which needs to be overcome by cutting off the fuel supply of the turbine engine.
Cutting off the supply is carried out generally by the closing of a valve arranged in a supply circuit that supplies a rail of injectors of the combustion chamber. This closing leads to an abrupt shutdown of the flow of fuel injected, which has the effect of producing a pressure wave that rises back along the supply circuit of the injectors in the direction opposite the normal direction of flow of the fuel and in the direction of the tanks of the aircraft.
The appearance of a pressure peak following the rise of this pressure wave to the tanks is not permitted as it would pose safety problems.
Conventionally, this disadvantage is overcome by equipping the fuel circuit with a fuel accumulator, arranged on a portion of the fuel circuit of the turbine engine, in order to absorb the energy produced by this pressure wave before it reaches the tanks.
Such an accumulator comprises a deformable enclosure, subjected to a pressurized gas, which is in contact with the fuel supply circuit via a connection pipe. In the event of an abrupt shutdown of the fuel supply, the pressure wave is passed into the connection pipe and compresses the deformable enclosure which then plays the role of a shock absorber, which has the effect of reducing the pressure peak in the supply circuit.
However, the effectiveness of such an accumulator is highly dependent on the installation thereof. Indeed, the longer and thinner the connection pipe is, the less effective the accumulator is. This problem is generally overcome by oversizing the accumulator, and even under these conditions, the latter is not always capable of performing a satisfactory dampening of the pressure peaks. Furthermore, oversizing the accumulator leads to an increase in the size thereof and to an increase in the mass thereof.
U.S. Pat. No. 4,729,360 describes a fuel accumulator with a deformable enclosure configured to confine in a sealed manner a gas, to reduce the pressure fluctuations in a fuel supply circuit of a vehicle. The housing that receives the deformable enclosure interrupts the pipe to form a bend with an upstream portion and a downstream portion of the pipe that is connected to the housing. The presence of this bend leads to the whole of the pipe being voluminous.
Supposing that the upstream and downstream portions of the pipe that are connected to the housing are aligned, the movable wall of the deformable enclosure will not be directed in the direction of the pressure wave that travels through the fuel pipe in the direction opposite the normal fuel flow. Consequently, this device cannot be, at the same time, not very voluminous and be capable of dampening such a wave with the maximum effectiveness.
Documents FR 1149443A and U.S. Pat. No. 4,911,204 describe fuel accumulators that operate according to a similar principle, and arranged coaxially with fuel circuit pipes. These accumulators comprise deformable enclosures housed in housings coaxial to the pipes, which communicate with these pipes via bores or ducts oriented radially with respect to the axis of the pipes. This configuration is not optimal, as it causes load losses in the pipes.